From: u.kleine-koenig@pengutronix.de (Uwe Kleine-König)
To: linux-arm-kernel@lists.infradead.org
Subject: 'bx lr' vs 'mov pc,lr'
Date: Mon, 14 Sep 2009 09:35:14 +0200 [thread overview]
Message-ID: <20090914073514.GA15883@pengutronix.de> (raw)
In-Reply-To: <94a0d4530909131847g2295b93by47de1785cc2f34b4@mail.gmail.com>
On Mon, Sep 14, 2009 at 04:47:35AM +0300, Felipe Contreras wrote:
> On Mon, Sep 14, 2009 at 3:20 AM, Jamie Lokier <jamie@shareable.org> wrote:
> > Felipe Contreras wrote:
> >> > Why do you want bx? ?bx isn't available on older CPUs.
> >>
> >> Isn't it faster? I don't know if it would make sense to try it on
> >> newer CPUs.
> >
> > That's interesting. ?Do you know if it's faster?
>
> Nope, I'm assuming because of this:
> http://newsgroups.derkeiler.com/Archive/Comp/comp.sys.arm/2006-04/msg00031.html
For ARM9EJ-S the docs can be found at
http://infocenter.arm.com/help/topic/com.arm.doc.ddi0222b/I1028171.html
. bx takes 3 cycles, mov (with dest=pc) takes 4 cycles.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-K?nig |
Industrial Linux Solutions | http://www.pengutronix.de/ |
next prev parent reply other threads:[~2009-09-14 7:35 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-13 21:55 'bx lr' vs 'mov pc,lr' Felipe Contreras
2009-09-13 22:15 ` Daniel Silverstone
2009-09-13 22:56 ` Felipe Contreras
2009-09-13 23:01 ` Russell King - ARM Linux
2009-09-14 0:11 ` Felipe Contreras
2009-09-13 22:58 ` Russell King - ARM Linux
2009-09-14 0:11 ` Felipe Contreras
2009-09-14 0:20 ` Jamie Lokier
2009-09-14 1:47 ` Felipe Contreras
2009-09-14 7:35 ` Uwe Kleine-König [this message]
2009-09-14 12:59 ` Felipe Contreras
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